How To Change Cams In A 96” Twin Cam Engine

Posted Wed, 07/01/2009 - 16:00 by administrator

The writer intends that this instruction be used in conjunction with the Harley service manual for the engine. It should not be regarded as a stand-alone instruction. If you don’t have a manual, get one. Don’t start without it – consider yourself warned. Read them both. If you choose not to do that, have your checkbook fully loaded and a pen handy.

Introduction and special tools

This process has been considerably simplified over what it was in the 88” Twin Cam engines. With one exception, special, job-specific tools are no longer required. Most particularly, it is no longer necessary to press the cam journals into roller bearings in the cam support plate; they are a smooth slip fit.

That is not necessary because there are no longer bearing assemblies in the cam support plate—the cam journals run in the bare aluminum of the plate now. (Harley calls that a bearing. Technically, it is, but it is not one in the sense that we have been accustomed to seeing.) The journals are supported on a film of oil fed through tiny passages in the plate into the “bearing.” As long as the oil supply is adequate this will serve just fine. However, the passages are quite small, and thus the need for the 5-micron oil filter called for in this engine.

The inner cam journals continue to run in needle bearings in the crankcase and the outer end of the crankshaft continues to run in a bronze bushing in the cam support plate. Harley has used a bushing in that application for decades.

There are only two special tools called for, pictured here. One should be purchased; the other can be easily and cheaply made.

On the right is a device to lock the pinion sprocket and the primary cam sprocket together to allow loosening the bolts that hold them in place. Harley advises against using makeshift jamming methods such as rags, screwdrivers, chunks of wood, fingertips, etc. in this application. The writer concurs—the tool is not expensive and using it avoids the chance of collateral damage to parts and body pieces being disassembled. He obtained his from George’s Garage (http://www.georges-garage.com/Engine_Tools.htm p/n3205200) at a price significantly less than other sources ($24 at this writing). It is Delrin plastic and works just fine.

On the left is a device to hold the valve lifters up in the bores while the cams are pulled. Harley recommends adapting an office-type bulldog clamp. Others have told the writer it works, but he could not make it so. Instead, for less than $5.00, he made the tool shown here from flat brass stock with hobby magnets super glued to it. It works.

Synopsis of work (Task numbers here have equivalent numbers in detailed explanation.)

1.Raise bike until rear wheel can be turned. Place transmission in 5th or 6th gear.

36.Start engine WATCHING OIL PRESSURE IMMEDIATELY. It should come up normally right away.

(i) For the tool to fit properly between the teeth of both sprockets the index dots on each sprocket must be aligned side-by-side. Achieve that by turning the rear wheel in 5th or 6th gear. Intuitively, it would seem that positioning should not make a difference, but it does.

Detailed How-To

1.Raise the bike until the rear wheel can be turned freely to rotate the engine for steps 5, 29, 30.

2.Remove right side cover and pull master fuse (see service manual).

3.Remove air cleaner cover. You could work around it, but why bother? It’s held on by one machine screw, the big one in the center. You need not remove the whole air cleaner.

4.Remove (or move out of the way) the exhaust system.

The writer was dealing with his 2007 Road Glide. The following is true for any of the FL bikes. It may be true for others.

·It is not necessary to completely remove the exhaust system, although that will simplify the actual removal of the cam cover and cam support plate. The writer believes removing the system is more trouble than dealing with limited clearance to remove those two items.

·Loosen (not remove) two clamps at rear of head pipe. One clamps the muffler to the head pipe; the other clamps the pipe to a support bracket.

·Remove nuts from studs holding head pipe to head at exhaust port. Let clamp slide free. Wiggle head pipe forward until mouth of the pipe can clear the studs. Twist it outwards and pull forward as far as possible – the frame down tube prevents removal. Stop there and move on to next step.

5.Remove spark plugs (so that engine can be rotated through by turning rear wheel.)

6.Remove pushrods (this procedure assumes they will be cut out.)

·DO NOT cut pushrods while under load –you may damage your engine or you. Neither is likely; either is possible. To avoid it is simple. Therefore, rotate engine until pushrod to be cut is on the base circle of the cam and can be spun freely by fingers. Now, cut it and take out the pieces. Repeat three more times, rotating engine each time.

·Use bolt cutters. DO NOT use hacksaw, abrasive cutter, acid, your pet beaver, Captain Midnight Laser Pistol, or anything else. The risk of steel junk in the lifter area and severe engine damage is simply too great to risk. Buy, rent, or borrow a 30” bolt cutter, period.

7.Lift and hold valve lifters in their bores (using special tool).

·If the magnets don’t reach the lifters, turn the engine over by hand to raise the lifters enough that the magnet can get them.

·The lifters do not have to be clear to the top of their bores, just enough to clear the cam lobes.

·If you somehow let a lifter fall into the cam chest you make sure it goes back into the hole it was in, and is properly oriented in the hole. See the manual for specifics and other information.

8.Remove the cam cover.

·There are ten screws, all the same length.

·Two of them are behind the exhaust pipe. With it moved out as you have done, they can be reached with the short end of an L-shaped Allen wrench. If clearance is still inadequate, modify the wrench by cutting or grinding off some of the short leg of the L.

·Loosen the cam cover from the engine by placing a piece of wood against the top front or back corner cover and rapping the wood with a hammer. DO NOT strike the cover directly, even with a soft hammer. You’d probably get away with it, but maybe not. Error would be expensive. NOTE: the cover has no dowel pins holding it in place, just the screws. Once they are out it is only stickiness of the gasket holding things together.

9.Pin primary cam chain tensioner to hold parts together. (Yellow arrow – insert wire in small hole to hold plunger in body when part is removed.)

10.Remove primary cam chain tensioner. NOTE: This part is held on by two #25 Torx fasteners (red horizontal arrows). They are made of SOFT aluminum or possibly Chinese chewing gum taken from under a theater seat.

The lower one is behind the exhaust pipe. It is impossible to reach with a Torx wrench, so here’s what I did. You can do it, too, or you can remove the exhaust system. Take out the top screw, carefully. I damn near stripped the head on mine. Then, using a brass drift, small hammer, and gentle hands, tap the top of the tensioner body to shift it away from the chain. Getting it off the chain is all you need to do. The shoe is not heavily spring-loaded—it will not go SPROING!!! and shoot pieces off into dark, distant corners of your shop.

11.Lock sprockets together with special tool and remove bolts holding them in place.

·You must first turn the engine over by hand until the indexing dots on the pinion sprocket and the primary cam sprocket are aligned. It is counterintuitive, but for some reason that makes a difference in whether or not the tool will fit.

·The tool’s teeth are cut to fit only one way. In this case, the head of the tool (the part facing you) has the letters GG (for George’s Garage) cast in. They should be right side up to fit.

12.Remove sprockets and primary cam chain from shafts as a unit. You will find spacers behind the sprockets. Note what the service manual has to say about them.

NOTE: I did not take a picture of this step. Therefore, this image from the Internet is of an 88” cam support plate, but screw positioning is the same. Follow the numbers to loosen or tighten the screws. IT MATTERS. Otherwise, you may warp the plate, rendering it expensively useless.

13.Remove four Allen head socket screws fastening cam support plate to oil pump. (Gray dots on image.) Follow sequence shown by numbers on illustration here. You will retighten in the same order.

14.Remove six Allen head socket screws fastening cam support plate to crankcase flange. (Black dots on image.) You will retighten in same order.

15.Remove cam plate and cams from cam chest. Cams will slip out of needle bearings in case. This is what you will see inside the cam chest.

·You will replace O-rings beside yellow arrows.

·The oil pump slides off the end of the crankshaft. You do not have to take it out, but if you are curious, go ahead. If you do it, though, you will find another O-ring to be replaced behind the pump, approximately where the red X is.

·These 3 O-rings are critical to maintaining proper oil pressure. Make sure they are replaced, and the new ones carefully installed – do not pinch them.

I did not take a picture of the back of the cam support plate at all, much less with the cams still in place. But here is another image – it is of a 96” cam support plate and cams, etc.

16.Pin secondary cam chain tensioner to hold parts together.

17.Remove and discard circlip from groove in the outer end of front camshaft. (Remember, when you’re looking at the back of the cam support plate front and rear are reversed.)

18.Remove two cams and secondary chain as a unit from cam support plate.

19.Remove cams from secondary cam chain.

20.OPTIONAL: Remove oil pump from crankshaft, disassemble and inspect. Reassemble as per instructions in service manual. It is not complicated.

21.Replace two o-rings (or three if oil pump was removed.)

22.OPTIONAL FOLLOWUP: Replace oil pump on crankshaft. CAUTION: There is a short tube on the back of the oil pump. It is the oil scavenge tube from the crankcase. It fits into the new O-ring you have placed in the crankcase. As you put the oil pump back be very careful that the tube fits properly into the new O-ring. If it is not done right, if the O-ring is pinched or cut, the oil pressure will not come up properly.

23.Place new cams into secondary chain. Observe alignment! The cam gears each have an indexing dot (yellow in picture – black or uncolored in reality.) Those dots MUST be precisely aligned to one another on a line drawn between the centers of each camshaft.

24.Place cams and chain into cam support plate.

NOTE: This is the big improvement over the 88” engine, where the cams must be pressed into ball bearing assemblies. For this engine, though, just lay the support plate flat on a clean shop rag, lightly lube the cam journals with motor oil and then slip them carefully into the cam support plate. Don’t go jamming and twisting; you want to maintain the nice, sharp edges on the bearings in the plate. Now, take a moment to make sure that you really, for sure, positively, beyond a doubt, got the dots on each cam gear properly aligned and that the alignment is exactly along a line drawn between the centers of the camshafts. The picture above is just right. Unless you like sudden, loud, expensive noises from your engine that let all the smoke out, you absolutely DO NOT want to install the cams out of time with one another. Now dribble some engine oil onto the chain and sprockets.

25.REMOVE PIN FROM SECONDARY CAM CHAIN TENSIONER!

26.Place hardened spacer (.100 thick) and a new circlip on end of front camshaft. Don’t try to cheap out and use the old circlip; t’aint worth it. You don’t have to use a Harley clip; just take the old one down to NAPA and get another one just like it. In fact, get two and save one for the next time. As usual with circlips in grooves, install it with the sharp edge of the hole facing out.

IF YOU DON’T HAVE A TORQUE WRENCH THAT MEASURES IN INCH-POUNDS GO BORROW, RENT, OR BUY ONE NOW! Do not try to use a ft/lb wrench with a range that runs up to 80 or 100 ft/lbs or whatever. The torque value called for on the machine screws in the next step is low, so low that a ft/lb wrench like most of us have is not accurate that far down the scale. See the service manual for the proper torque values.

27.Install cams and cam support plate in engine. Make sure that the needle bearings in the case still have lots of oil in them. There is a specific, critical torque sequence to be followed for the four oil pump screws and the six case flange screws. It is shown on the image you’ve seen, up above. Follow it! You DO NOT want to warp the plate that the cams ride in by improperly torquing the plate.

NOTE: That being said . . . the bottom two screws cannot be reached with a torque wrench as long as the exhaust is in place. You may want to take the exhaust off after all. I didn’t. I know that my wrist is pretty well educated when it comes to torquing bolts, so I simply tightened them down what felt like enough to me using an Allen wrench. If you are not confident of your ability to feel torque, DON’T DO IT MY WAY. Take the exhaust off and use a torque wrench.

28.Place pinion sprocket and primary cam sprocket into primary cam chain with indexing dots facing each other precisely. They are the critical alignment in this process; the relationship between pinion gear and primary cam (and thus overall cam timing) are set based on having these sprockets properly oriented to one another.

·The pinion sprocket has a flat in the hole that matches up with a flat on the pinion shaft.

·The primary cam sprocket has an integrated key (a wide tooth) machined into the splines that must match up with a wide slot on the rear camshaft.

·Turn the engine (thus, the pinion shaft) with the rear wheel and then the rear cam (the cam, not the cam sprocket, which is now in the chain) with your fingers until things are lined up so that you can slip the sprockets into place. . . Do this without rotating the primary cam sprocket out of alignment with pinion sprocket within the chain. (This varies slightly from the procedure described in the service manual. Either will work.) When both sprockets are in place on the shafts the index marks on each, and a line scribed on the support plate between them, should all be aligned precisely.

30.When you are absolutely confident that the sprockets are properly aligned, bolt them in place. Do this step only after you have followed the procedure in the service manual to assure that the sprockets are in alignment within the chain – see Critical Note below.

NOTE: The two flange bolts are different lengths. Each has a spacer that goes behind the flange. The spacers are different thicknesses and have different hole diameters. These are specially-hardened Harley parts. They are not interchangeable. Do NOT try to replace them with stuff from the hardware store or your collection of junk bolts and washers. When you find that one of the spacers doesn’t fit its shaft, you’ve got the wrong spacer. Do NOT try to drill it out to fit. The short bolt and thin spacer attach the small sprocket to the pinion shaft.

NOTE: To achieve the proper torque on these bolts you must make sure the underside of the flange, both sides of the spacer, and the surface of the sprocket are clean. Then put a dab of oil on the underside of the flange.

NOTE: DO place one drop of red loctite (#262) on the threads of each bolt. Clean the threads first.

Critical Note Before Going On: The two sprockets must line up side to side so that the chain will run true. Since you are replacing the cams you should have no confidence that it will be so when using the old spacer behind the primary cam sprocket. It might be, but don’t bet your engine on it—CHECK THE ALIGNMENT! Instructions are found on page 3-46 of the service manual.

To achieve alignment, there are spacers on the shafts between the sprockets and the cam support plate. The spacer behind the pinion sprocket is .100 thick—it’s marked, and it ALWAYS goes behind the pinion sprocket, letters against the plate. Harley sells spacers of varying thickness to go behind the primary cam sprocket to move it in or out to align with the pinion shaft sprocket.

Read the service manual for instructions on how to get proper spacing and for part numbers for the various thickness spacers.

Do it NOW or you may regret it LATER alongside the road on a dark night with cold rain running down your neck like a snowman taking a leak and the batteries in your flashlight deader than JFK.

31.Replace primary cam chain tensioner and REMOVE PIN.

NOTE: Remember how the heads on the Torx screws on that tensioner are soft, and how the exhaust pipe is in the way of reaching the lower bolt? Well, things didn’t change while you swapped the cams, bubba. To solve that problem I replaced the top screw with an Allen head screw. I torqued that one, since I could reach it with a torque wrench. The bottom one, though, sticks out far enough that even an Allen wrench won’t fit, much less a torque wrench. So I put in a hex-head bolt and trusted my educated wrist again. You might want to use a crow’s foot extension on your torque wrench to reach in there and get it right.

31.Install and adjust new pushrods. (Make sure that the O-rings that the pushrod tubes seat in are still in place.) Adjust the pushrods to the manufacturer’s specifications.

NOTE: If you lost the data card they came with, or you don’t know what kind they are at all and don’t know how many turns out to make, just remember this: the nominal amount you want to extend them is .100 (1/10th) of an inch for all Harley hydraulic lifters. No more than that, but a little less (down to about .070 in my opinion) is okay. So before you put them in, take your micrometer (or take them to someone who has one) and see how many turns it takes to extend them that much.

NOTE: The upper pushrod tubes (or covers) on the Twin Cam motor are longer than the ones on the Evo or Shovelhead. What this means for you and me is that it is difficult to adjust pushrods’ lengths because the lower end of the tube is so close to the valve lifter cover. But it can be done, with a lot of swearing. Or, you can buy shorter tubes from Harley (p/n 17634-99), which lets you slide them farther up the pushrod to make room for your fingers to fumble with the adjuster.

32.Turn engine through one complete rotation by turning rear wheel gently by hand to assure there is no interference anywhere. With the plugs out you should feel no resistance except a tiny amount each time a lifter comes up and has to open a valve against its spring pressure. If you feel more than just a little bit, and especially if there is a “click” or worse, a “clank” with it, make sure your checkbook is fully loaded and the safety off before you push it any farther. Better you should find out why that’s going on.

33.Install cam cover with a new gasket. Strangely enough, they aren’t expensive – yet. And the air cleaner cover, and hook the pipes back up.

34.Install spark plugs. And oh, yeah: put the wires back on. It won’t start worth a damn with them hanging loose. Don’t ask me how I know. That holds true for the master fuse, too.

35.Start engine WATCHING OIL PRESSURE IMMEDIATELY. It should come up normally right away. If it doesn’t, shut down and find out why not.

And that’s all. Let me say again: USE THESE INSTRUCTIONS WITH THE SERVICE MANUAL.